I take it you mean urine. Urine stains are a problem stain and need to be dealt with properly if you are to have any succes. Often the urine has soaked riight through into the backing and floor below. Both these need to be treated as well to prevent ongoing odour problems.
Quite often the urine or whatever the customer has used has removed some of the colour and caused pile damage. You need to pre-qualify this with the customer and not raise their expectations.
First of all you need to use a urine neutraliser. This will help stabilise the carpet dye as well as disolving the uric salts. You realy need to pull back the carpet and do the underlay and floor. Let this do its work then extract as much as you can using a detergent suitable for the fibre being worked on. After you have extracted and extracted using a hand tool, including the back of the carpet a good odour kill product need to be applied. This needs to be left to soak into the floor and spray applied to the underlay and carpet, back and front. This procedure may enble you to obtain a satisfactory result and because of the work involved charged for appropriately. Please note that a couple of attempts may be required on different days.